The contents of 12 serial segments of the gastrointestinal tract of the pig will be analyzed after feeding a conventional or experimental diet, to determine the effects of diet and time after feeding. Measurements will include liquid and particulate markers administered with the meal as well as lactic acid, VFA, osmolality and major inorganic electrolytes. VFA transport will also be examined, using mucosa isolated from the stomach and large intestine. Results will be used to characterize microbal digestion and the secretion and absorption of H20 by the digestive tract of this species.